Method of coating metallic powder particles

ABSTRACT

A method and system for coating metallic powder particles is provided. The method includes: disposing an amount of metallic powder particulates within a fluidizing reactor; removing moisture adhered to the powder particles disposed within the reactor using a working gas; coating the powder particles disposed within the reactor using a precursor gas; and purging the precursor gas from the reactor using the working gas.

BACKGROUND OF THE INVENTION

1. Technical Field

The present disclosure relates to processing metallic powder particlesin general, and to processes for coating metallic powder particles inparticular.

2. Background Information

Aluminum alloy materials are widely used in many areas including theaerospace industry for their light weight structural properties and inheat transfer products due to high thermal conductivity. Additivemanufacturing of aluminum alloy powders, in particular, via laser basedadditive processes, has drawn increasing attention. A significantchallenge in the laser additive manufacturing of certain alloy powders(e.g., certain aluminum alloy powders) is the high degree to whichenergy in the form of light waves within a laser beam are reflected awayfrom the alloy powder. As a result of the reflectance, the energy of thereflected light does not appreciably contribute to the additive process.In some instances, it may not be possible to sufficiently increase theintensity of existing laser equipment to overcome the reflectance issue.Even in those instances where the laser intensity can be increased, sucha practice can create new detrimental issues; e.g., a higher intensitylaser can overheat the powder and cause the powder particles to “ballup” and consequently create a non-uniform deposition layer. Also as aresult of the reflectance, present additive manufacturing processes aresometimes limited to certain types of materials. With respect toaluminum alloys, for example, additive manufacturing processes are todaytypically limited to cast aluminum alloy compositions. These castaluminum alloy compositions have low reflectance properties that allowthem to be used in additive processes, but possess undesirablemechanical and thermal properties.

In addition, alloy powders adsorbed with water moisture can causesignificant quality issues of the deposits made by additivemanufacturing processes. These issues include porosity, cracks, andblisters.

It would be beneficial to resolve the aforesaid issues and therebyimprove additive manufacturing processes and make it possible toadditively manufacture certain alloy powders, including additional typesof aluminum alloy compositions.

SUMMARY OF THE INVENTION

According to one aspect of the present disclosure, a method of coatingmetallic powder particles is provided. The method includes: disposing anamount of metallic powder particulates within a fluidizing reactor;removing moisture adhered to the powder particles disposed within thereactor using a working gas; coating the powder particles disposedwithin the reactor with a material present within a precursor gas; andpurging the precursor gas from the reactor using the working gas.

In a further embodiment of the foregoing aspect, the coating includescoating the powder particles with the material in an amount such thatthe coated powder particles have a level of reflectivity that isacceptable for subsequent processing of the coated powder particleswithin an additive manufacturing process.

In a further embodiment of the foregoing aspect, the metallic powderparticles are aluminum alloy. They may include at least one of aluminum5056, aluminum 6061, aluminum 7075, or proprietary aluminum alloys suchas Pandalloy® aluminum alloy. Pandalloy® (also referred to herein as“PANDALLOY”) is a registered trademark of United TechnologiesCorporation.

In a further embodiment of any of the foregoing embodiments of thepresent disclosure, the precursor gas comprises silicon. The precursorgas may include at least one of silane (SiH₄), disilane (Si₂H₆),chlorosilane (H₃ClSi), or dichlorosilane (SiH₂Cl₂).

In a further embodiment of any of the foregoing embodiments of thepresent disclosure, the working gas is at least one of nitrogen (N₂) orreducing gas hydrogen (H₂).

In a further embodiment of any of the foregoing embodiments of thepresent disclosure, removing moisture adhered to the powder particlesdisposed within the reactor using working gas includes heating theworking gas to a predetermined temperature.

According to another aspect of the present disclosure, a method ofcoating metallic powder particles is provided. The method includes:providing a system having a fluidizing reactor, a working gas source, aprecursor gas source, and a processor adapted to execute instructions tocontrol and monitor operation of the system, wherein the processor is incommunication with a memory operable to store the executableinstructions; disposing an amount of metallic powder particulates withina fluidizing reactor; controlling the system to remove moisture adheredto the powder particles disposed within the reactor using a working gasprovided from the working gas source; controlling the system to coat thepowder particles disposed within the reactor using a precursor gasprovided from the precursor gas source; and controlling the system topurge the precursor gas from the reactor using the working gas.

In a further embodiment of the foregoing aspect, the step of controllingthe system to coat the powder particles includes coating the powderparticles with the material present in the precursor gas in an amountsuch that the coated powder particles have a level of reflectivity thatis acceptable for subsequent processing of the coated powder particleswithin an additive manufacturing process.

In a further embodiment of the foregoing aspect, the metallic powderparticles are aluminum alloy. The may include at least one of aluminum5056, aluminum 6061, aluminum 7075, or PANDALLOY aluminum alloy.

In a further embodiment of any of the foregoing embodiments of thepresent disclosure, the precursor gas comprises silicon. The precursorgas may include at least one of silane (SiH₄), disilane (Si₂H₆),chlorosilane (H₃ClSi), or dichlorosilane (SiH₂Cl₂).

In a further embodiment of any of the foregoing embodiments of thepresent disclosure, the working gas is at least one of nitrogen (N₂) orreducing gas hydrogen (H₂).

In a further embodiment of any of the foregoing embodiments of thepresent disclosure, removing moisture adhered to the powder particlesdisposed within the reactor using working gas includes heating theworking gas to a predetermined temperature.

In a further embodiment of any of the foregoing embodiments of thepresent disclosure, the memory is at least one of a non-volatile memoryor a non-transitory computer readable media in communication with theprocessor.

In a further embodiment of any of the foregoing embodiments of thepresent disclosure, the method further includes cooling the coatedpowder particles.

According to another aspect of the present disclosure, a system forcoating metallic powder particles is provided. The system includes atleast one working gas source, at least one precursor gas source, atleast one fluidizing reactor, and a processor. The fluidizing reactor isin communication with the working gas source and the precursor gassource. The processor is adapted to execute instructions to controloperation of the system. The executable instructions are operable tocontrol the system to: remove moisture adhered to the powder particlesdisposed within the reactor using working gas provided from the workinggas source; coat the powder particles disposed within the reactor usinga precursor gas provided from the precursor gas source; and purge theprecursor gas from the reactor using the working gas.

In a further embodiment of the foregoing aspect, the executableinstructions are operable to control the system to provide a mixture ofthe precursor gas and the working gas and to coat the powder particlesdisposed within the reactor using the mixture.

In a further embodiment of any of the foregoing embodiments of thepresent disclosure, the system further includes an escaped powderparticle collector vessel.

In a further embodiment of any of the foregoing embodiments of thepresent disclosure, the system further includes at least one heatsource, and the executable instructions are operable to control the heatsource to heat the working gas to a predetermined temperature, and toremove moisture adhered to the powder particles disposed within thereactor using the working gas heated to the predetermined temperature.

In a further embodiment of any of the foregoing embodiments of thepresent disclosure, the system further includes a liquid bubblerdisposed such that working gas and precursor gas exiting the reactortravels through the liquid bubbler.

In a further embodiment of any of the foregoing embodiments of thepresent disclosure, the metallic powder particles are an aluminum alloythat includes at least one of aluminum 5056, aluminum 6061, aluminum7075, or PANDALLOY aluminum alloy, and the precursor gas includes atleast one of silane (SiH₄), disilane (Si₂H₆), chlorosilane (H₃ClSi), ordichlorosilane (SiH₂Cl₂).

The foregoing features and elements may be combined in variouscombinations without exclusivity, unless expressly indicated otherwise.These features and elements as well as the operation thereof will becomemore apparent in light of the following description and the accompanyingdrawings. It should be understood, however, the following descriptionand drawings are intended to be exemplary in nature and non-limiting.

BRIEF DESCRIPTION OF THE DRAWINGS

Various features will become apparent to those skilled in the art fromthe following detailed description of the disclosed non-limitingembodiments. The drawings that accompany the detailed description can bebriefly described as follows:

FIG. 1 is a schematic illustration of an embodiment of the presentsystem.

FIG. 2 is a flow chart of an embodiment of the present disclosure.

FIG. 3 is a graph of depicting a calculation of the percentage ofsilicon coated on a powder (Y-axis) as a function of the powderparticulate size (X-axis).

DETAILED DESCRIPTION

It is noted that various connections are set forth between elements inthe following description and in the drawings (the contents of which areincluded in this disclosure by way of reference). It is noted that theseconnections are general and, unless specified otherwise, may be director indirect and that this specification is not intended to be limitingin this respect. A coupling between two or more entities may refer to adirect connection or an indirect connection. An indirect connection mayincorporate one or more intervening entities.

According to the present disclosure, a system 10 and method forpreparing a metallic material (e.g., aluminum alloy powder) for additivemanufacturing is provided. For the purpose of describing the presentdisclosure, the metallic material is detailed hereinafter as being analuminum alloy powder. The present disclosure provides particularutility regarding the processing of aluminum alloy particles 12 (e.g.,because of the reflectivity of aluminum alloy powders), but theapplicability of the present disclosure is not limited to aluminumalloys. The term “powder” as used herein refers to matter configured inthe form of fine discrete particles. The aforesaid particles 12 mayassume a variety of different particle sizes; e.g., particles having adiameter in the range of about one micrometer to one hundred and fiftymicrometers (i.e., 1-150 μm). The present disclosure is typically usedto process particles 12 of a given size (i.e., substantially all of theparticles are “x” diameter) during a particular processing application,but the present disclosure is not limited to processing particles 12 ofa specific size. Non-limiting examples of aluminum alloy powders thatmay be processed using the present disclosure include aluminum 5056,aluminum 6061, aluminum 7075, PANDALLOY aluminum alloy, etc.

FIG. 1 illustrates a schematic illustration of an exemplary system 10operable to prepare a metallic material for further processing; e.g.,additive manufacturing. The system 10 includes a fluidized bed reactor14, at least one working gas source 16, at least one precursor gassource 18, a mass flow control device 20, an escaped powder collectorvessel 22, a liquid (e.g., water) bubbler 24, and various valves 26 andflow measuring devices (e.g., pressure gauges 28, temperature sensingdevices 30, etc.) disposed within piping 32 connecting the aforesaiddevices. The piping 32 may include bleed line 33, outlet lines 35, vents37, etc. In addition, a processor 34 may be included in the system 10 incommunication with one or more of the aforesaid devices, valves, andflow measuring devices to control and monitor the system 10. Theaforesaid system 10 is an example of a system configuration, and thepresent disclosure is not limited to the specific system illustrated.

The fluidized bed reactor 14 (hereinafter referred to as the “reactor14”) may assume a variety of different configurations. For example, thereactor 14 may be configured to have a single vessel or configured tohave both an inner vessel and an outer vessel. The schematic system 10shown in FIG. 1 illustrates a reactor 14 configured with both an innervessel 36 and an outer vessel 38. In alternative embodiments, thereactor 14 may include a plurality of independent vessels; e.g., eachdisposed to fluidize a different powder material. The reactor 14 mayinclude a heat source 40 to heat a fluidizing gas (schematicallydepicted in FIG. 1), or a heat source may be provided independent of thereactor 14. One or more temperature sensing devices 30 (e.g.,thermocouples) may be disposed inside the reactor 14 or may be disposedin the piping 32 leading to and/or from the reactor 14 to sense thetemperature of the gases entering the reactor 14, the gas powder mixturewithin the reactor 14, the gas powder mixture exiting the reactor 14.The reactor 14 may include a distributor (e.g., a porous plate 42)through which gases are introduced into the vessel (e.g., the innervessel 36).

The working gas source 16 provides at least one gas that is inert and/orone that creates a “reducing atmospheric environment” with respect tothe processing of the particular material. The term “reducingatmospheric environment” or “reducing gas” as used herein refers to agas that is operable to create an environment in which oxidation isprevented by removal of oxygen or other oxidizing gases or vapors.Nitrogen (N₂) or hydrogen (H₂) are non-limiting examples of gases thatcan be used to process aluminum alloy powders; e.g., Nitrogen (N₂) is anon-limiting example of an inert gas and hydrogen (H₂) is a non-limitingexample of a reducing gas. As will be described hereinafter, the workinggas may be used as a medium to heat the powder particles 12 and toremove adsorbed moisture from the powder. The working gas source 16 mayassume any form (e.g., pressurized vessel, etc.) appropriate to providethe working gas as required.

The precursor gas source 18 provides one or more gases that include atleast one material that coats the powder particles 12 during processingas will be discussed below. The material(s) from the precursor gas(es)that coats the powder particles 12 is one that, when applied insufficient coating thickness, results in the coated powder particles 12having a level of reflectivity that is acceptable for subsequentprocessing of the coated particles 12 within an additive manufacturingprocess. The specific thickness of the coating on the particles 12 mayvary depending on factors such as the coating material, the material ofthe powder particle, the additive manufacturing process for which thepower particles are being prepared for, etc. The present disclosure isnot limited to any particular coating thickness. A precursor gas thatenables the deposition of a silicon coating on the powder particles 12is particularly useful when the present disclosure is used to coataluminum or aluminum alloy powder particles 12. Specific non-limitingexamples of a precursor gas that enables the deposition of a siliconcoating on the powder particles 12 include silane (SiH₄), disilane(Si₂H₆), chlorosilane (H₃ClSi), dichlorosilane (SiH₂Cl₂), etc. Theprecursor gas may be used as a medium to heat the powder particles 12(or to maintain the temperature of the powder particles 12 duringprocessing). The precursor gas source 18 may assume any form (e.g.,pressurized vessel, etc.) appropriate to provide the first precursor gasas required.

In some embodiments, the present disclosure may utilize a source 44 ofone or more additional precursor gases (hereinafter referred tocollectively as a source of a “second precursor gas”), each of which canbe used to coat the particles 12 of the particular powder material.Examples of acceptable precursor gases that enable the deposition of asilicon coating on aluminum or aluminum alloy powder particles 12 areprovided above. The source 44 of the second precursor gas may assume anyform (e.g., pressurized vessel, etc.) appropriate to provide the secondprecursor gas as required.

The mass flow control device 20 is a standard device operable to controlflow of gas within a conduit (e.g., piping 32). One or more mass controldevices 20 may be used to control the delivery of working gas, firstprecursor gas, and second precursor gas to the reactor 14.

The liquid bubbler 24 is operable to decrease the temperature of and/orneutralize, gases introduced into the bubbler 24, such as working gasesor precursor gases purged from piping upstream of the reactor 14, orworking gases or precursor gases purged from the reactor 14. In thelatter case, the aforesaid gases may pass through the escaped powdercollector vessel 22 prior to entering the bubbler 24. The liquiddisposed within the bubbler 24 may depend on the particular applicationat hand; e.g., water, etc.

The escaped powder collector vessel 22 is a vessel operable to collectpowder particles 12 that have escaped from the reactor 14 duringprocessing. For example, in those instances where the working gas isused as a medium to heat the powder particles 12 and is subsequentlypurged from the reactor 14, the purged working gas may have smallamounts of powder particles 12 entrained within the purged working gas.The escaped powder collector vessel 22 is operable to collect theaforesaid powder particles 12 entrained within the purged working gas.

As indicated above, the present system 10 may be controlled, monitored,etc. using a controller having a processor 34. The processor may beadapted (e.g., programmed) to provide signals to and/or receive signalsfrom various components disposed within the system 10 (e.g., valves 26,mass control flow devices 20, the reactor 14, flow measuringdevices—e.g., pressure gauges 28, temperature sensing devices 30, etc.—,gas sources, etc.) and use such signals to control and/or monitor thesystem 10. The processor 34 may include one or more central processingunits (CPUs) adapted (e.g., programmed) to selectively executeinstructions necessary to perform the control/monitor functionsdescribed herein. The functionality of processor 34 may be implementedusing hardware, software, firmware, or a combination thereof. Theprocessor 34 may be in communication with (e.g., included with theprocessor) a memory 46 operable to store the aforesaid programming(e.g., instructions), which memory 46 may be non-volatile or may be inthe form of non-transitory computer readable media in communication withthe processor 34. A person skilled in the art would be able to adapt(e.g., program) the processor 34 to perform the functionality describedherein without undue experimentation.

An exemplary method according to the present disclosure is describedhereinafter to illustrate the utility of the present disclosure. Themethod description provided below is provided in terms of the exemplarysystem 10 described above. The present disclosure is not limited to theaforesaid exemplary system or the method described below.

Now referring to FIG. 2, according to a method embodiment of the presentdisclosure an amount of powder particles 12 is introduced into thereactor 14 from a powder source (step 50); e.g., introduced into theinner reactor vessel 36. In terms of preparing a powder for subsequentuse in an additive manufacturing process, non-limiting examples ofacceptable aluminum alloy powders include aluminum 5056, aluminum 6061,aluminum 7075, and PANDALLOY aluminum alloy.

The system 10 is controlled to purge the reactor 14 of ambient air andprovide a working gas (e.g., N₂) environment within the reactor vessel36 containing the powder (step 52). The working gas may be introducedinto the reactor 14 through piping 32 connecting the working gas source16 and the reactor 14. In the embodiment shown in the schematic, theworking gas enters the reactor 14 within the annular region 48 disposedbetween the inner vessel 36 and the outer vessel 38 via inlet 49. Thesystem 10 is controlled to provide the working gas at a predefined massflow using the mass flow control device 20 and valves 26. The workinggas is heated prior to or after introduction into the reactor vesselusing one or more heat sources 40. The powder particles 12 are“fluidized” within the reactor 14 by the working gas (i.e., suspendedwithin the reactor 14 by the gas traveling within the reactor 14, suchthat the fluidized powder 12 acts like a fluid). The specific travelpath of the working gas within the reactor 14 may vary depending on theconfiguration of the reactor 14; e.g., in the reactor embodiment shownin the schematic of FIG. 1, the working gas travels within the annularregion 48 disposed between the inner vessel 36 and the outer vessel 38,enters and passes through the inner vessel 36 (via the distributor 42),and exits the reactor 14. The exiting working gas is directed throughinto the liquid bubbler 24 where it is cooled and/or neutralized. Thetemperature of the working gas within the reactor 14 is sensed andcontrolled using the one or more temperature sensing devices 30 (e.g.,thermocouples) and the heat source 40 to provide a gas temperaturesufficient to cause any moisture (e.g., water) adsorbed to the powder tobe liberated from the powder and removed from reactor 14 with theexiting working gas (step 54). During this fluidization process theindividual particles 12 of the powder are separated from one another,and are prevented from sintering because the particles 12 of powder arenot maintained in close proximity to each other. The fluidizing of thepowder particles 12 is performed at a temperature and for a period oftime duration adequate to remove the adsorbed moisture; i.e., dry thepowder to an acceptable moisture level.

Once the adsorbed moisture is removed from the particles, the system 10may be controlled to purge the working gas (now containing the moisture)from the reactor 14. The present disclosure is not limited to anyparticular process for removing the moisture; e.g., a given volume ofworking gas may be maintained within the reactor 14 for a given periodof time to collect the moisture and subsequently purged, or a volume ofworking gas may be continuously passed through the reactor 14 to collectthe moisture, etc. Any powder particles 12 entrained within the purgedgas may be collected in the escaped powder collector vessel 22. Thesystem 10 is controlled to introduce a precursor gas into the reactor 14via piping 32 at a predefined mass flow using the mass flow controldevice 20 and valves 26. Depending upon the application at hand, thesystem 10 may be controlled such that 100% of the gas entering thereactor 14 is the precursor gas, or a mixture of working gas and theprecursor gas, or a mixture of one or more of working gas, a firstprecursor gas, or a second precursor gas. In an application whereinaluminum alloy powder is being processed for subsequent use in anadditive manufacturing process, a mixture of a precursor gas(silane—SiH₄) and working gas (N2) may be used.

Within the reactor vessel 36, the precursor gas decomposes and depositsa coating on the fluidized powder particles 12 within the vessel (step56). A precursor gas that enables the deposition of a silicon coating onthe powder particles 12 (e.g., silane) is particularly useful whenprocessing aluminum or aluminum alloy powder particles 12 for severalreasons. Silane works well as a precursor gas because it starts todecompose into silicon and hydrogen at a mild condition of 250° C.Silicon is a composition element within certain aluminum alloys (e.g.,aluminum 6061 and 7075). The thickness of the particle coating can becontrolled within the system 10 by varying one or more processparameters; e.g., the amount of time that the fluidized powder particles12 are subjected to the precursor gas, the mixture ratio of theprecursor ratio and working gas, etc. Consequently, the amount ofsilicon added to the powder via the coating process can be controlled sothat the amount of silicon in the processed powder (e.g., weight % ofsilicon within the combined coating and unprocessed powder) isappropriate to arrive at the desired alloy composition; i.e., when theprocessed powder is subsequently used in an additive manufacturingprocess, the additively manufactured material has the desiredcomposition percentages. Using the present disclosure, it is possibletherefore to add a relatively small percentage of silicon to a powderand the powder will be a viable candidate for additive manufacturing;i.e., reflectance is not an issue. As a result, certain aluminum alloys(i.e., alloys having a low silicon content; wrought Al alloys) becomeadditive manufacturing candidates, which alloys were not previouslycandidates. FIG. 3 is a graph that depicts a calculation of thepercentage of silicon coated on aluminum alloy powder (Y-axis) as afunction of the powder particulate size (X-axis). The curves 62A, 62B,62C within the graph are for different silicon coating thicknesses. Thethicknesses indicated in the graph are provided to illustrate thefunctionality of the present disclosure, and the present disclosure isnot limited thereto. The calculation exhibits how the thickness of thesilicon coating alters the silicon composition percentage within thealloy. Hence, the material properties of a silicon coated aluminum alloycan be maintained.

In addition, the silicon applied via a fluidizing process using silane(or other precursor gases comprising silicon) has a reflectance that isapproximately less than 50% of the reflectance of aluminum at typicalwavelengths used in the additive manufacturing process (e.g.,wavelengths between about 400 and 1000 nanometers; 400-1000 nm). Hence,the silicon coating applied via the present disclosure substantiallyavoids the reflectance problem associated with additively manufacturinguncoated aluminum alloy powders. For at least these reasons, the presentdisclosure improves (or makes it possible to) additive manufacturing ofstructures using certain aluminum alloy powders.

Still further, a coating applied using the present disclosure providesan effective barrier for preventing re-adsorption of moisture onto thepowder. As a result, the coated powder can be stored in a typicalproduction environment for an extended period of time without adversemoisture adsorption.

Once the powder has been sufficiently coated in the fluidizing process,the system 10 is controlled to stop the flow of precursor gas. In manyinstances, the system 10 may be subsequently controlled to continue (orprovide) a flow of working gas through the reactor 14. The subsequentflow of working gas is typically provided at a lower temperature. Theworking gas, therefore, both purges the precursor gas from the system 10and cools the processed powder within the reactor 14 (step 58). Finally,the system 10 can be controlled to purge the cooled powder from thereactor 14, and the cooled powder can be subsequently collected from thereactor 14 (step 60) and stored in containers for subsequent processing;e.g., additive manufacturing.

The foregoing descriptions are exemplary rather than defined by thelimitations within. Various non-limiting embodiments are disclosedherein, however, one of ordinary skill in the art would recognize thatvarious modifications and variations in light of the above teachingswill fall within the scope of the appended claims. It is therefore to beunderstood that within the scope of the appended claims, the disclosuremay be practiced other than as specifically described. For that reasonthe appended claims should be studied to determine true scope andcontent.

What is claimed is:
 1. A method comprising: disposing an amount ofmetallic powder particulates within a fluidizing reactor; removingmoisture adhered to the metallic powder particulates disposed within thereactor using a working gas; coating the metallic powder particulatesdisposed within the reactor with a material present within a precursorgas subsequent to said removing of moisture; and purging the precursorgas from the reactor using the working gas, wherein the coating includescoating the metallic powder particulates with the material in an amountsuch that the coated metallic powder particulates have a level ofreflectivity that is acceptable for subsequent processing of the coatedmetallic powder particulates within an additive manufacturing process.2. The method of claim 1, wherein the metallic powder particulates arealuminum alloy.
 3. The method of claim 2, wherein the aluminum alloy isselected from the group consisting of aluminum 5056, aluminum 6061, oraluminum
 7075. 4. The method of claim 1, wherein the precursor gascomprises silicon.
 5. The method of claim 4, wherein the precursor gasis selected from the group consisting of silane (SiH₄), disilane(Si₂H₆), chlorosilane (H₃ClSi), or dichlorosilane (SiH₂Cl₂).
 6. Themethod of claim 1, wherein the removing moisture adhered to the metallicpowder particulates disposed within the reactor using working gasincludes heating the working gas to a predetermined temperature.
 7. Amethod comprising: providing a system having a fluidizing reactor, aworking gas source, a precursor gas source, and a processor adapted toexecute instructions to control and monitor operation of the system,wherein the processor is in communication with a memory operable tostore the executable instructions; disposing an amount of metallicpowder particulates within the fluidizing reactor; controlling thesystem to remove moisture adhered to the metallic powder particulatesdisposed within the reactor using a working gas provided from theworking gas source; controlling the system to coat the metallic powderparticulates disposed within the reactor with a material present in aprecursor gas provided from the precursor gas source; and controllingthe system to purge the precursor gas from the reactor using the workinggas, wherein the controlling the system to coat the metallic powderparticulates includes coating the metallic powder particulates with thematerial in an amount such that the coated metallic powder particulateshave a level of reflectivity that is acceptable for subsequentprocessing of the coated metallic powder particulates within an additivemanufacturing process.
 8. The method of claim 7, wherein the metallicpowder particulates are aluminum alloy.
 9. The method of claim 8,wherein the aluminum alloy is selected from the group consisting ofaluminum 5056, aluminum 6061, or aluminum
 7075. 10. The method of claim7, wherein the precursor gas comprises silicon.
 11. The method of claim10, wherein the precursor gas is selected from the group consisting ofsilane (SiH₄), disilane (Si₂H₆), chlorosilane (H₃ClSi), ordichlorosilane (SiH₂Cl₂).
 12. The method of claim 10, wherein theworking gas is at least one of an inert gas or a reducing gas.